Ok,

res.json is not a function

is a weird bug that I solved by deleting and then bringing back this block of code that is running inside my `getServerSideProps`:

await superTokensNextWrapper(
        async next => {
            return await verifySession()(context.req, context.res, next);
        },
        context.req,
        context.res
    );

    const { userId } = context.req.session;

(deleted an issue that I solved already - I was import getUserById from the supertokens-auth-react package, not supertokens-node)